Philip Pullman, author of the best-selling His Dark Materials trilogy, is leading a protest against the introduction of age guidance for children's books.

The guidelines are being introduced by leading publishers but have caused such dismay amongst the literary community that more than 80 authors, illustrators, librarians, teachers and booksellers have joined together in protest.

An online petition at www.notoagebanding.org says that the idea is "ill-conceived" and "damaging to the interests of young readers".

It goes on: "We take this step to disavow publicly any connection with such age-guidance figures, and to state our passionately-held conviction that everything about a book should seek to welcome readers in and not keep them out."

Mr Pullman told The Daily Telegraph: "I don't mind anybody having an opinion about my books. I don't mind a bookseller deciding they are for this age group or that, or a teacher giving one of my books to a child because they think it is appropriate.

"But I don't want to see the book itself declaring officially, as if with my approval, that it is for readers of 11 and upwards or whatever. I write books for whoever is interested. When I write a book I don't have an age group in mind.

"I have had letters from children of seven who say they have read all the way through His Dark Materials and they have an astonishing knowledge of it. But not every child is the same. A child of nine might be tentative and unsure about reading, and to give them a book that says 9+ will reinforce their sense of failure. The book should be suited to the individual child."

Anyone unsure as to whether a particular book is appropriate should ask the bookseller, Mr Pullman said.

"There are lots of clues on the cover, but if they are unsure they can always ask a specialist. Booksellers know the books they have for sale, they know their readers and they can talk to a parent or grandparent who comes in. If a grandparent says, 'My granddaughter is a very advanced reader but rather timid and scared by monsters,' then they can advise."

Mr Pullman's own publisher, Scholastic, has agreed not to put age banding on his books. "A month or so ago I had a letter saying books were going to have this. I wrote back and said, 'Mine aren't.' They were very good and said if I had a problem, then they wouldn't do it. But, talking to other authors, I discovered that not everybody was in my position.

"I signed this petition because I believe passionately in what it says. It is an act of solidarity not only with other authors, but with booksellers and librarians. It is not precisely a campaign, because a campaign has an aim which it seeks to achieve. We have already achieved our aim, which is to say publicly that publishers can do this if they want to, but not in our name."